A fração solúvel de ST2 (sST2) é a isoforma circulante do ST2, um receptor membro da família das interleucinas-1. O sST2 é considerado um biomarcador cardíaco, pois é induzido mecanicamente pelo estiramento de cardiomiócitos e fibroblastos em situações de estresse miocárdico secundário à sobrecargas de volume ou de pressão, podendo ser detectado no soro. Este biomarcador tem demonstrado valor prognóstico em humanos, sendo considerado um importante preditor de mortalidade independente. Embora possua capacidade limitada como teste diagnóstico quando utilizado isoladamente, as concentrações séricas de sST2 apresentam-se aumentadas em pacientes humanos com ICC aguda, motivo pelo qual sua utilidade tem sido estudada em associação a outros biomarcadores como o NT-proBNP e a troponina I (cTnI). Entretanto, ainda não há estudos clínicos avaliando o sST2 em cães com degeneração valvar crônica de mitral (DVCM). Portanto, a proposta deste estudo foi determinar a utilidade do sST2, comparado ao NT-proBNP e a cTnI, para a avaliação de cães predispostos ou em diferentes estágios da DVCM. Para tanto, foram selecionados 151 cães em diferentes estágios de DVCM. Os animais foram submetidos à exame clínico, testes laboratoriais, radiografias torácicas, eletrocardiografia, ecodopplercardiografia, mensuração de pressão arterial sistólica e dosagens dos biomarcadores sST2, NT-proBNP e cTnI. Os resultados deste estudo demonstraram que as concentrações de sST2 foram maiores nos cães com ICC secundária a DVCM, em relação aos cães sem ICC. Entretanto, quando os cães foram agrupados de acordo com os estágios da DVCM, não houve diferença nas mensurações de sST2 entre os grupos. As mensurações de NT-proBNP e a cTnI foram maiores tanto nos cães com ICC, em relação aos cães sem ICC, quanto nos estágios mais avançados da DVCM. Observou-se correlação entre o sST2 e os biomarcadores NT-proBNP e cTnI, assim como entre sST2 e variáveis ecodopplercardiográficas de avaliação da função diastólica. Na análise de curva ROC para o diagnóstico de ICC, as áreas sob a curva (AUC) foram de 0,66 para o sST2, 0,86 para NT-proBNP e 0,76 para cTnI. Na avaliação de prognóstico, observou-se que o grupo de cães com mensurações de sST2 maiores que 40 pg/mL apresentou maior ocorrência de óbito, comparado ao grupo com menores valores de sST2. Concluiu-se que o desempenho do sST2, como teste diagnóstico para ICC, isoladamente, foi limitado e inferior aos outros biomarcadores estudados. Entretanto, a correlação observada entre sST2, NT-proBNP, cTnI e variáveis ecodopplercardiográficas, sugere que o sST2 pode acrescentar valor diagnóstico em uma análise de regressão multivariada. O sST2 parece possuir utilidade como marcador prognóstico independente, sendo preditor de mortalidade em cães com DVCM. / The soluble fraction of ST2 (sST2) is the circulating isoform of ST2, a member of the interleukin-1 (IL-1) receptor family. Soluble ST2 is considered a cardiac biomarker, which is induced mechanically by the stretch of cardiomyocytes and fiblobasts in situations of myocardial stress, due to volume or pressure overload, and may be measured in serum. This biomarker has shown prognostic value in human cardiology, and is considered an important independent mortality predictor. Although it holds limited diagnostic capacity by itself, serum concentration of sST2 is increased in acute heart failure human patients, reason why its utility has been studied in association to other biomarkers as NT-proBNP and cardiac troponin I (cTnI). However, studies assessing sST2 in dogs with chronic mitral valve disease (CMVD) are still lacking. Therefore, this study aimed to determine the utility of sST2, compared to NT-proBNP and cTnI, for assessment of dogs predisposed to or in different stages of CMVD. With this purpose, 151 dogs in different stages of CMVD were recruited and submitted to clinical exam, laboratory tests, thoracic radiography, electrocardiography, echocardiography, systolic arterial blood pressure assessment and measurement of the biomarkers sST2, NT-proBNP and cTnI. The results demonstrate that sST2 concentration was higher in dogs in congestive heart failure (CHF) secondary to CMVD compared to dogs without CHF. However, when dogs were stratified according to CMVD stages, it was not possible to differentiate the groups based on sST2 concentrations. NT-proBNP and cTnI concentrations were higher in CHF dogs compared to non-CHF dogs, as well as in more advanced stages of CMVD. There was correlation between sST2 and NT-proBNP and cTnI, and also between sST2 and diastolic function echocardiographic variables. Analysis of ROC curve for HF diagnosis showed areas under the curve (AUC) of 0,66 for sST2; 0,86 for NT-proBNP and 0,76 for cTnI. As for prognosis assessment, sST2 concentrations higher than 40 pg/mL indicated higher mortality compared to groups with lower sST2 values. We conclude that sST2 performance as a stand alone diagnostic test is limited and inferior to the other studied biomarkers. However, the correlation observed between sST2, NT-proBNP, cTnI and echocardiographic variables, suggests that sST2 may add diagnostic value in a multivariate regression analysis. sST2 seems to be a useful independent prognostic marker, and mortality predictor in dogs with CMVD.

A fração solúvel de ST2 (sST2) é a isoforma circulante do ST2, um receptor membro da família das interleucinas-1. O sST2 é considerado um biomarcador cardíaco, pois é induzido mecanicamente pelo estiramento de cardiomiócitos e fibroblastos em situações de estresse miocárdico secundário à sobrecargas de volume ou de pressão, podendo ser detectado no soro. Este biomarcador tem demonstrado valor prognóstico em humanos, sendo considerado um importante preditor de mortalidade independente. Embora possua capacidade limitada como teste diagnóstico quando utilizado isoladamente, as concentrações séricas de sST2 apresentam-se aumentadas em pacientes humanos com ICC aguda, motivo pelo qual sua utilidade tem sido estudada em associação a outros biomarcadores como o NT-proBNP e a troponina I (cTnI). Entretanto, ainda não há estudos clínicos avaliando o sST2 em cães com degeneração valvar crônica de mitral (DVCM). Portanto, a proposta deste estudo foi determinar a utilidade do sST2, comparado ao NT-proBNP e a cTnI, para a avaliação de cães predispostos ou em diferentes estágios da DVCM. Para tanto, foram selecionados 151 cães em diferentes estágios de DVCM. Os animais foram submetidos à exame clínico, testes laboratoriais, radiografias torácicas, eletrocardiografia, ecodopplercardiografia, mensuração de pressão arterial sistólica e dosagens dos biomarcadores sST2, NT-proBNP e cTnI. Os resultados deste estudo demonstraram que as concentrações de sST2 foram maiores nos cães com ICC secundária a DVCM, em relação aos cães sem ICC. Entretanto, quando os cães foram agrupados de acordo com os estágios da DVCM, não houve diferença nas mensurações de sST2 entre os grupos. As mensurações de NT-proBNP e a cTnI foram maiores tanto nos cães com ICC, em relação aos cães sem ICC, quanto nos estágios mais avançados da DVCM. Observou-se correlação entre o sST2 e os biomarcadores NT-proBNP e cTnI, assim como entre sST2 e variáveis ecodopplercardiográficas de avaliação da função diastólica. Na análise de curva ROC para o diagnóstico de ICC, as áreas sob a curva (AUC) foram de 0,66 para o sST2, 0,86 para NT-proBNP e 0,76 para cTnI. Na avaliação de prognóstico, observou-se que o grupo de cães com mensurações de sST2 maiores que 40 pg/mL apresentou maior ocorrência de óbito, comparado ao grupo com menores valores de sST2. Concluiu-se que o desempenho do sST2, como teste diagnóstico para ICC, isoladamente, foi limitado e inferior aos outros biomarcadores estudados. Entretanto, a correlação observada entre sST2, NT-proBNP, cTnI e variáveis ecodopplercardiográficas, sugere que o sST2 pode acrescentar valor diagnóstico em uma análise de regressão multivariada. O sST2 parece possuir utilidade como marcador prognóstico independente, sendo preditor de mortalidade em cães com DVCM. / The soluble fraction of ST2 (sST2) is the circulating isoform of ST2, a member of the interleukin-1 (IL-1) receptor family. Soluble ST2 is considered a cardiac biomarker, which is induced mechanically by the stretch of cardiomyocytes and fiblobasts in situations of myocardial stress, due to volume or pressure overload, and may be measured in serum. This biomarker has shown prognostic value in human cardiology, and is considered an important independent mortality predictor. Although it holds limited diagnostic capacity by itself, serum concentration of sST2 is increased in acute heart failure human patients, reason why its utility has been studied in association to other biomarkers as NT-proBNP and cardiac troponin I (cTnI). However, studies assessing sST2 in dogs with chronic mitral valve disease (CMVD) are still lacking. Therefore, this study aimed to determine the utility of sST2, compared to NT-proBNP and cTnI, for assessment of dogs predisposed to or in different stages of CMVD. With this purpose, 151 dogs in different stages of CMVD were recruited and submitted to clinical exam, laboratory tests, thoracic radiography, electrocardiography, echocardiography, systolic arterial blood pressure assessment and measurement of the biomarkers sST2, NT-proBNP and cTnI. The results demonstrate that sST2 concentration was higher in dogs in congestive heart failure (CHF) secondary to CMVD compared to dogs without CHF. However, when dogs were stratified according to CMVD stages, it was not possible to differentiate the groups based on sST2 concentrations. NT-proBNP and cTnI concentrations were higher in CHF dogs compared to non-CHF dogs, as well as in more advanced stages of CMVD. There was correlation between sST2 and NT-proBNP and cTnI, and also between sST2 and diastolic function echocardiographic variables. Analysis of ROC curve for HF diagnosis showed areas under the curve (AUC) of 0,66 for sST2; 0,86 for NT-proBNP and 0,76 for cTnI. As for prognosis assessment, sST2 concentrations higher than 40 pg/mL indicated higher mortality compared to groups with lower sST2 values. We conclude that sST2 performance as a stand alone diagnostic test is limited and inferior to the other studied biomarkers. However, the correlation observed between sST2, NT-proBNP, cTnI and echocardiographic variables, suggests that sST2 may add diagnostic value in a multivariate regression analysis. sST2 seems to be a useful independent prognostic marker, and mortality predictor in dogs with CMVD.

A ce jour, un certain nombre d'adénomes hypophysaires somatotropes échappent encore au contrôle de la maladie. Il reste nécessaire d'étudier plus finement les différentes voies de contrôle de la sécrétion hormonale et de la prolifération tumorale afin d'identifier des traitements alternatifs susceptibles de contrôler ces symptômes tumoraux. De même, un certain nombre de patients porteurs de prolactinomes (environ 10%), à l'origine de dysfonctionnement gonadique et sexuels, échappent au contrôle de l'hypersécrétion de prolactine par les traitements actuels. Pour ces deux types de tumeurs, s'ajoutent des complications neurologiques consécutives à l'accroissement des volumes tumoraux. Dans une perspective de contrôle de l'hypersécrétion tumorale nous nous sommes intéressés à deux stratégies faisant intervenir un transfert de gènes dans les cellules. POU1F1 est un facteur de transcription crucial pour le développement et le maintien des lignages somatotrope, lactotrope et thyréotrope et son expression est retrouvée dans les adénomes hypophysaires. De plus, des mutations de ce gène, notamment le mutant dominant négatif R271W, ont été identifiés chez des patients présentant des déficits hypophysaires combinés en GH, en PRL et en TSH. Une première partie de ma thèse a donc porté sur l'étude du transfert du mutant dominant négatif de POU1F1 par un vecteur lentiviral dans les tumeurs hypophysaires somatotropes et lactotropes afin d'évaluer son impact sur la sécrétion hormonale et sur la viabilité cellulaire. Nous avons montré que l'inactivation de ce facteur de transcription entrainait une diminution de la viabilité cellulaire et de la sécrétion de toutes les tumeurs testées. / To this date, some somatotroph adenomas do not respond to the current treatment of pituitary tumors. It still necessary to study the different ways to control the hormonal secretion and the tumor progression to identify alternate therapy capable to manage these symptoms. Likewise, some patient with prolactinomas (about 10%) responsible of gonad and sexual dysfunction do not respond to the control of prolactin hypersecretion. In addition, some neurological complications are finding due to the neighboring structures compression for both of these tumors. To better control the hormonal secretion we investigate two different strategies involving a gene transfer in the cells. POU1F1 is a major transcription factor involved in the pituitary development and the management of somatotroph, thyreotroph and lactotroph cell lines. Its expression is found in pituitary adenomas belonging of these 3 cell lines. Moreover some mutations like the R271W mutant are identified in patients with combined pituitary hormonal deficiency (CPHD). In the first part of my thesis we transfer this dominant negative mutant via a lentiviral transfer in the somatotroph and lactotroph adenomas to evaluate its impact on hormonal secretion and cell viability. We show an inhibitory effect of the POU1F1 inactivation on the secretion and the cell viability of all our tumors. Somatostatin analogs are the major medical therapy for somatotroph adenomas and control GH secretion in 60% of these patients. Octreotide resistance is highly correlated to a low expression of the sst2 receptor.

Introduction: Inflammatory cardiomyopathy (ICM) frequently leads to myocardial fibrosis, resulting in permanent deterioration of the left ventricular function and an unfavorable outcome. Soluble suppression of tumorigenicity 2 receptor (sST2) is a novel marker of inflammation and fibrosis in cardiovascular tissues. sST2 was found to be helpful in predicting adverse outcomes in heart failure patients with reduced ejection fraction. The aim of this study was to determine the association of sST2 plasma levels with cardiac magnetic resonance (CMR) and echocardiography imaging features of left ventricular impairment in ICM patients, as well as to evaluate the applicability of sST2 as a prognosticator of the clinical status in patients suffering from ICM. Methods: We used plasma samples of 89 patients presenting to the Heart Center Leipzig with clinically suspected myocardial inflammation. According to immunohistochemical findings in endomyocardial biopsies (EMB) conducted in the context of patients’ diagnostic work-up, inflammatory cardiomyopathy was diagnosed in 60 patients (ICM group), and dilated cardiomyopathy in 29 patients (DCM group). All patients underwent cardiac catheterization for exclusion of coronary artery disease and CMR imaging on 1.5 or 3 Tesla. sST2 plasma concentration was determined using ELISA. Results: Mean plasma concentration of sST2 in the whole patient cohort was 45.8 ± 26.4 ng/mL (IQR 27.5 ng/mL). In both study groups, patients within the highest quartile of sST2 plasma concentration had a significantly lower left ventricular ejection fraction (LV-EF) compared to patients within the lowest sST2 plasma concentration quartile (26 ± 11% vs. 40 ± 13%, p = 0.05 for ICM and 24 ± 13% vs. 51 ± 10%, p = 0.004 for DCM). sST2 predicted New York Heart Association (NYHA) class III/IV at 12 months follow-up more efficiently in ICM compared to DCM patients (AUC 0.85 vs. 0.61, p = 0.02) and was in these terms superior to NT-proBNP and cardiac troponin T. ICM patients with sST2 plasma concentration higher than 44 ng/mL at baseline had a significantly higher probability of being assigned to NYHA class III/IV at 12 months follow-up (hazard ratio 2.8, 95% confidence interval 1.01–7.6, log rank p = 0.05). Conclusion: Plasma sST2 levels in ICM patients reflect the degree of LV functional impairment at hospital admission and predict functional NYHA class at mid-term follow-up. Hence, ST2 may be helpful in the evaluation of disease severity and in the prediction of the clinical status in ICM patients.

Although, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) represents one of the biggest challenges in the world today, the exact immunopathogenic mechanism that leads to severe or critical Coronavirus Disease 2019 (COVID-19) has remained incompletely understood. Several studies have indicated that high systemic plasma levels of inflammatory cytokines result in the so-called “cytokine storm”, with subsequent development of microthrombosis, disseminated intravascular coagulation, and multiorgan-failure. Therefore, we reasoned those elevated inflammatory molecules might act as prognostic factors. Here, we analyzed 245 serum samples of patients with COVID-19, collected at hospital admission. We assessed the levels of heat shock protein 27 (HSP27), soluble suppressor of tumorigenicity-2 (sST2) and 20S proteasome at hospital admission and explored their associations with overall-, 30-, 60-, 90-day- and in-hospital mortality. Moreover, we investigated their association with the risk of ventilation. We demonstrated that increased serum sST2 was uni- and multivariably associated with all endpoints. Furthermore, we also identified 20S proteasome as independent prognostic factor for in-hospital mortality (sST2, AUC = 0.73; HSP27, AUC = 0.59; 20S proteasome = 0.67). Elevated sST2, HSP27, and 20S proteasome levels at hospital admission were univariably associated with higher risk of invasive ventilation (OR = 1.8; p < 0.001; OR = 1.1; p = 0.04; OR = 1.03, p = 0.03, respectively). These findings could help to identify high-risk patients early in the course of COVID-19.

Le stress a une fonction adaptative mais son influence délétère sur la santé physique,cognitive et mentale lorsqu’il se présente de façon excessive et/ou chronique est aujourd’huireconnue. De très nombreux travaux ont démontré que le jeune enfant, l’adolescent et le sujetâgé y sont particulièrement vulnérables. L’objectif de cette thèse a été de déterminer s’ilexiste une sensibilité au stress chronique chez l’adulte selon l’âge au moment de l’exposition.Le modèle de stress chronique léger et imprédictible mis au point chez la souris a été utilisé.Les impacts à court et long-terme (sujet âgé), ont été déterminés en analysant les troublessomatiques, hédoniques, anxieux, dépressifs et cognitifs, caractéristiques du syndrome destress. Contrairement à l’idée selon laquelle l’adulte serait plus résistant et plus résilient auxperturbations induites par le stress, les résultats de cette thèse démontrent qu’une période destress à l’âge adulte produit des effets délétères drastiques non seulement immédiats maiségalement à long terme. Toutefois, l’adulte d’âge moyen serait plus résistant et plus résilientrelativement aux adultes jeunes ou d’âge avancé qui présentent une symptomatologie plusmarquée. La sévérité des symptômes anxieux initialement générés par le stress est corrélée àla fois avec la persistance des troubles et la modification des marques de répression géniquedans l’hippocampe indiquant la présence d’une signature épigénétique de l’épisode de stress àlong terme. Des études récentes ont suggéré l’implication de la somatostatine centrale dans lesrégulations émotionnelles et relient la vulnérabilité au stress chronique des neuronessomatostatinergiques avec le développement de troubles anxio-dépressifs. Les résultats decette thèse ont permis d’identifier l’inhibition à la fois de l’axe HPA et des comportementsanxio-dépressifs par les récepteurs sst2 et sst4 de l’hippocampe. Les profils comportementauxinduits par l’utilisation d’agonistes sélectifs ou par la délétion de ces deux récepteurssuggèrent l’existence de deux voies de régulation interagissant respectivement avec lessystèmes sérotoninergique (voie sst2) et noradrénergique (voie sst4), l’une régulantprincipalement l’état anxieux, l’autre les désordres dépressifs et cognitifs. Ainsi, cette thèseétaye l’importance de la pathogénicité du stress chronique chez l’adulte et l’importance desrégulations neuroendocriniennes et cognitivo-émotionnelles par les récepteurs sst2 et sst4, unespécificité qui doit être prise en considération dans l’utilisation et le développement destraitements somatostatinergiques ciblant / Stress has an adaptive function but it can have also deleterious effects on physical,cognitive and mental health when its intensity and/or chronicity increase. A large body ofevidence supports the idea that young children, adolescents and aged people are highlysensitive to stress. The aim of this study was to determinate if a critical period of sensitivity tostress may be evidenced during adulthood. The Unpredictable Chronic Mild Stress protocoldeveloped in the mouse was used. Short and long-term impacts of stress were quantified byassessing somatic, hedonic, anxious, depressive and cognitive troubles which arecharacteristic of a stress syndrome. Unlike the view that adults are resistant and resilient tostress, the results presented in this thesis show that a stress period during adulthood inducesimmediate and long-lasting deleterious effects. However, middle-aged adults were moreresistant and more resilient than younger or older subjects which both displayed a more severesymptomatology. The anxiety level initially induced by chronic stress is correlated with thepersistence of troubles and with modifications of gene repression marks in the hippocampus,indicating the presence of an epigenetic signature of the chronic stress episode in the longterm.Recent studies have suggested that central somatostatin is involved in emotionalregulations, linking the vulnerability of somatostatinergic neurons to chronic stress with theinstatement of anxio-depressive disorders. We showed herein that hippocampal sst2 and sst4receptor subtypes mediate the inhibition of HPA axis and improve anxio-depressivebehaviors. Behavioral patterns induced by either selective agonists or deletions of thesereceptors suggest that two regulatory pathways respectively interact with the serotoninergicsystem (sst2) and the noradrenergic system (sst4). In addition, sst2 receptors mainly regulateanxiety whereas sst4 is mainly involved in the regulation of cognitive and depressivedisorders. As a whole, this thesis corroborates the idea that chronic stress has pathogeniceffects even in adulthood and highlights the importance of neuroendocrine and cognitivoemotionalregulations by sst2 and sst4 receptor subtypes, a specificity that has to beconsidered in the use and the development of somatostatin treatments targeting HPAderegulations and stress-related disorders.